System and method for disposal of digital media

ABSTRACT

A system and method are described for rendering Compact Discs (CDs) and Digital Video Discs (DVDs) unreadable. Embodiments comprise a frame, a guide for constraining motion of the frame with respect to a disc, and at least one scraping element. Scraping elements may be positioned to damage the disc volume descriptor while the frame moves in a constrained manner relative to the disc. The guide may comprise a spindle which engages the center hole of a disc to hold the frame in a radially-fixed position. A scraping element on the frame damages the disc as the disc rotates relative to the frame. The guide may be integrated, such that the frame comprises a slot through which the disc passes. A scraping element inside the slot damages a disc as it passes through. Embodiments are hand operated, not motorized, and some have no moving parts. Embodiments also function with non-optical media.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a divisional of U.S. patent application Ser. No. 11/450,751,filed Jun. 9, 2006 now U.S. Pat. No. 8,000,582, titled “System andMethod for Disposal of Digital Media”, and claims priority thereto.

TECHNICAL FIELD

The invention relates generally to computer security devices, and morespecifically to devices for destruction of computer-readable media.

BACKGROUND OF THE INVENTION

Disposal of intact Compact Discs (CDs) and Digital Video Discs (DVDs),including CD-Rs, CD-RWs, DVD-Rs and DVD-RWs, risks disclosure ofinformation contained on the media, similar to the risks faced duringdisposal of intact paper documents. The paper security problem has beenlargely addressed, with the widespread availability of relativelyinexpensive paper shredders for home, business and industrialenvironments. However, an equivalently reliable and cost-effectivesolution for rendering discs unreadable is not in widespread use.

As CD and DVD writers are becoming more affordable, there is an increasein the use of these types of discs for storage of confidentialinformation. Businesses store trade secrets and personal informationthat is subject to privacy restrictions. Home users often writefinancial data and highly personal information on CDs and DVDs. If theseare placed in the trash in an intact state, the confidential informationmay then be read by anyone who removes the discs from the trash.

Common methods to render a disc unreadable include burning, pulverizing,shattering, snapping, grinding and scratching the label side of the discinto the data layer. Burning and pulverizing may be quite effective inrendering a disc unreadable. Unfortunately, those methods may requireexpensive equipment. Shattering and snapping can be difficult for peoplewithout either the required strength or tools. Additionally, shatteringor snapping a disc presents a risk of injury from sharp, flying shards.Multiple models of disc grinders are available, although their size,cost and requirement for electric power may limit their desirability forcertain potential users.

Scratching into the data layer can often be done easily with any sharpinstrument. However, it presents risks, including injury andunintentional damage to other surfaces. Further, the damage to the discmay not be complete enough to render a disc unreadable. One reason thatscratching a disc may not be adequate is that a typical disc user maynot be aware of the physical layout of the data on a CD or DVD surface,and therefore may not sufficiently damage the critical data areas.

A CD typically contains a volume descriptor in sector 16, which iswithin a fraction of an inch of the innermost portion of theoptically-readable section of the disc. Disc readers typically firstread the volume descriptor, also known as an index, to determine thecontents of the disc. If this section is damaged or missing, themajority of disc readers may be unable to read the disc. However, due toits small size and its location near the innermost part of theoptically-readable area, it is easy to miss with uncontrolled, randomscratching. A disc with an intact volume descriptor may still bereadable, and files whose data area has not been adequately damaged maybe fully recoverable. Therefore, simply scratching a disc randomly witha sharp instrument does not provide safe, quality-controlleddestruction.

BRIEF SUMMARY OF THE INVENTION

Embodiments of the invention allow for a reliably consistent level ofdamage by guiding a scraping element across at least one predeterminedarea of a disc, such as the volume descriptor. Embodiments of theinvention require no motors and may have no moving parts. That is, someembodiments of the invention may be rigid devices that move as a singleunit relative to a disc, while holding at least one scraping elementthat scrapes the disc during the motion. Some embodiments, however, maycomprise flexible scraping element(s) that flex or partially retractinto cavities in response to pressure from a disc against the scrapingelements. Relative motion may be rotational, straight across, or evencurved, resulting in one or more scraping paths that form arced,straight, waved, looped lines or a combination thereof.

The relative positions allowed between a scraping element and a disc maybe constrained such that relative motion between the scraping elementand the disc is constrained for at least part of the motion. Therelative motion between a scraping element and a disc may be constrainedby using a guide to constrain relative motion between the disc and aframe that holds the scraping element. The constraint may serve to alignthe disc with the scraping element(s). Embodiments of the inventionallow for multiple types of guides, including a spindle that engages thecenter hole of a disc and allows only rotational motion. The spindleholds the frame in a radially-fixed position, such that a scrapingelement moves in an arced scraping path at a predefined radius. Theradius of the scraping path may correspond to the radius at which thevolume descriptor may be found, or any other part of a disc targeted fordamage.

Embodiments of the invention may also comprise at least one guide thatprotrudes from the frame to abut the edge of a disc. Such a guide mayconstrain the relative position of the frame when the frame spans a discat its widest point. Since the position of the guide may be fixedrelative to the frame, and the position of a scraping element may alsobe fixed relative to the frame, the position of the scraping element maythen be fixed relative to the edge of the disc. A pressure element maybe provided, which holds a disc against the scraping elements. In someembodiments, guides that abut opposing edges of a disc may form arectangular slot along with a pressure element and a frame holding thescraping elements. A disc passing through the slot will then have itsmotion constrained by the inner dimensions of the slot. Scrapingelements on both the frame and the pressure element can ensure that bothsides of a disc are damaged.

Embodiments of the invention may comprise multiple scraping elements toprovide multiple scraping paths. A certain number of paths may bedesired to achieve a particular level of damage, such that the data areasustains damage at some desired density.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, reference isnow made to the following descriptions taken in conjunction with theaccompanying drawings, in which:

FIG. 1 shows an embodiment of the invention;

FIG. 2 shows damage done to a disc by the embodiment of FIG. 1;

FIG. 3 shows another embodiment of the invention;

FIG. 4 shows damage done to a disc by the embodiment of FIG. 3;

FIG. 5 shows options for various embodiments of the invention;

FIG. 6 shows a method for using an embodiment of the invention; and

FIG. 7 shows a method for using an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

In many situations, it may only be necessary to destroy a disc's volumedescriptor, or file index, in order to provide the desired level ofdestruction. In other situations, destroying both the file index and aportion of the data area, leaving other portions of the data areauntouched, may suffice. That is, it may not be necessary to render adisc entirely unreadable by all equipment, in order to achieve asecurity goal. Some equipment and software is available to enablereading a disc with a damaged volume descriptor and rebuilding much ofthe disc's content. However, not every disposal situation requiresaddressing the threat posed by such equipment and software. Rather,based on the data density and locations of data on a disc, a number ofscraping elements may be provided to ensure that specific locations or aminimum percentage of the disc surface is damaged.

FIG. 1 shows disc scraper 10, comprising frame 100 and spindle 101 thatengages the center hole of a disc. Spindle 101 protrudes sufficientlybeyond any other protrusions from the frame in order to pass through thedisc's hole, and is sized to fit the hole. When a disc is placed overspindle 101, frame 100 may rotate with respect to the disc, but cannotmove radially with respect to the disc. That is, while the frame is in aradially-fixed position with respect to the disc, either the disc or theframe may rotate, or both. Spindle 101 should be sized to limit lateralmovement between a disc and the frame, but should not be so tight in thedisc that it causes unnecessary drag during rotation.

Scraping elements 102 a and 102 b are positioned between 21 and 23millimeters (mm) from the center axis of spindle 101, in order to scrapethe volume descriptor. If scraping elements 102 a and 102 b are oppositethe center axis of spindle 101 from each other, then rotating the frameonly half a circle will trace an entire circle on the disc, scraping theentire volume descriptor. Operation of scraper 10 requires a user topress a disc by hand, or another suitable method, against scraper 10 androtate the disc and scraper 10 relative to each other.

Scraping elements 103 a-d are positioned further than 25 mm from thecenter axis of spindle 101, in order to damage the data area of a discoutside the volume descriptor. Any number of scraping elements may beused, based on the desired scratching or scraping density and the widthof each scraping element. Scraping elements 102 a and b and 103 a-d areshown as pointed, stylus-type sharp points, however, any shape thatwould damage the disc could be used. Some shapes could remove morematerial from the disc than sharp points, but wider shapes couldincrease the resistance to rotating the frame. For example, a blade thatis approximately 2 mm wide could scrape the entire width of the volumedescriptor, but without the resistance from a blade that spanned theentire optically-readable portion of the disc.

Note that scraper 10 has no moving parts. That is, while scraper 10moves as a unit with respect to a disc, frame 100, spindle 101 andscraping elements 102 a-103 d do not move relative to each other. It ispossible that any of scraping elements 102 a-103 d, which are shown asrigidly attached to frame 100, could be made with flexible material.However, as defined herein, a rigidly-attached, flexing element is not amoving part. Further, spindle 101 of could be adapted such that at leasta portion of spindle 101 rotates along with a disc with respect to frame100. This could be accomplished by either having a rotating joint at thepoint where spindle 101 is coupled to frame 101, or by having a sleevethat fits over spindle 101 such that the sleeve stays fixed in positionrelative to a disc, but rotates relative to frame 101.

FIG. 2 shows the damage done to disc 20 by scraper 10 of FIG. 1. Disc 20comprises center hole 201 and optically-readable portion 200. Centerhole 201 fits over spindle 101, as described above. Optically-readableportion 200 is shown as having sustained damage from scraper 10. Acircle comprising arcs 202 a and 202 b has been scraped by scrapingelements 102 a and 102 b, indicating that disc 20 and scraper 10 haverotated at least half of a circle relative to each other. Had disc 20and scraper 10 not rotated half of a circle, arcs 202 a and 202 b wouldnot touch ends to form a complete circle. Arcs 203 a-d are due to thescraping paths of scraping elements 103 a-d. Disc 20 may retain intactdata, but the damage is extensive enough to prevent many disc readersfrom reading it.

FIG. 3 shows disc scraper 30, another embodiment of the invention withno moving parts. Scraper 30 comprises frame 30 with slot 301 andscraping elements 302, 303 a, 303 b and 304 a-d. Slot 301 is sized toallow a disc to pass through with minimal or no lateral clearance. Thelack of lateral clearance will ensure that scraping elements 302, 303 a,303 b and 304 a-d cross predefined portions of a disc when the widestportion of the disc enters the slot. Prior to that, and after the widestportion of the disc has passed through frame 30, the disc may havelateral movement. Further, a disc may have some rotational motion as itpasses through scraper 30, so scraping paths traced by scraping elements302, 303 a, 303 b and 304 a-d may not be straight. Rather, scrapingpaths may be waved lines, arcs, and even looped lines. However, whateverscraping paths may be, they will cross predefined locations when thewidest part of the disc is constrained to pass through the slot withoutany lateral movement.

As shown in FIG. 3, scraping element 302 is approximately in the centerof the widest dimension of slot 301. Scraping element 302 will thentrace a scraping path across the center point of the disc. As scrapingelement 302 crosses from the optically-readable portion of a disc towardthe center hole of the disc, it will damage the volume descriptor.Scraping elements 303 a and 303 b may be positioned to trace scrapingpaths that are tangential to the innermost portion of theoptically-readable portion of the disc, thereby scraping a largerportion of the volume descriptor than scraping element 302. Typicaldiscs would require scraping elements to be placed between 21 and 23 mmfrom the center of the widest dimension of slot 301.

In order for scraping elements 302, 303 a and 303 b to damage the volumedescriptor, a disc must be inserted nearly half way into slot 301. Intypical operation, though, a disc may be passed entirely through scraper30, ensuring damage to the volume descriptor. At the half way depth ofinsertion, the sides of frame 300 constrain the position of a disc to becentered in slot 301. That is, the sides of frame 300 act as guides forthe disc, to constrain its lateral motion as it moves relative to frame300. If slot 301 is sized for typical CDs and DVDs, it will beapproximately 12 centimeters (cm) wide, placing scraping elements 303 aand 303 b between 97 and 143 mm from an edge of slot 301.

Other scraping elements, such as 304 a-d may be provided to damage adata area other than the volume descriptor. Further, scraping elementsmay also be placed on the opposing side of slot 301 from scrapingelements 302, 303 and 304. The opposing side of frame 300 may providepressure to force a disc surface up against scraping elements 302, 303and 304. Since a typical disc is approximately 1 mm thick, slot 301 maybe between 1.5 and 5 mm on its narrow dimension, to allow for the heightof scraping elements 302, 303 and 304, and any scraping elements on theopposing side of slot 301. Scraping elements on both sides of slot 301allow scraper 30 to operate effectively, no matter which side of thedisc faces scraping elements 302, 303 and 304.

FIG. 4 shows the damage done to disc 40 by scraper 30 of FIG. 3.Optically-readable portion 200 of disc 40 is shown as having sustaineddamage from scraper 30. Scraping path 400 is due to scraping element302, and crosses the volume descriptor, near the innermost section ofportion 200, twice. Scraping paths 401 a and 401 b are due to scrapingelements 303 a and 303 b, and damage the volume descriptor more thanpath 400, since they run tangential to the innermost section of portion200. Scraping paths 402 a-d are due to scraping elements 304 a-d, anddamage portion 200 outside the volume descriptor region. Scraping paths400-400 d are shown as predominantly straight lines, however, since disc40 may have unconstrained rotational motion relative to fame 300, thescraping paths may not be straight. Rather, paths 400-400 d may bearbitrary lines, constrained only to pass at a certain distance from theouter edge of the disc when the disc is at the half way point throughslot 301.

FIG. 5 shows various options for disc scraper 50, another embodiment ofthe invention that guides a disc using the disc edge, similar to theembodiment shown in FIG. 3. Scraper 50 comprises frame 500 and scrapingelements 502-504 b coupled to frame 500. Scraper 50 is shown with guide505 a, protruding from frame 500, along with optional guide 505 b andoptional pressure elements 506 a and 506 b. Optional pressure elements506 a and 506 b are shown with optional scraping elements 507 a and 507b, and are optionally spring-loaded, using springs 508 a and 508 b, inorder to provide pressure for a disc against scraping elements 502-504b. In order to damage the volume descriptor of a typical disc, scrapingelements 502-503 b should be between 97 mm and 143 mm from guide 505 a.This ensures that when guide 505 a is against an edge of the disc, andscraping elements 502-503 b cross the central area of the disc, theywill also contact the volume descriptor.

Guide 505 b is optional because is it possible to align scrapingelements 502-503 b to damage a volume descriptor by pressing only guide505 a against the outer edge of a disc on one side. Further, it ispossible for a user to maintain pressure on a disc against scrapingelements 502-504 b similar to the operation of scraper 10 of FIG. 1,without optional pressure elements 506 a and 506 b. Pressure elements506 a and 506 b are shown as separated, rather than a single piecespanning from guide 505 a to guide 505 b. If pressure elements 506 a and506 b were connected to form a single piece, scraper 50 would thencomprise a closed slot, similar to scraper 30 of FIG. 3. Scrapingelement 504 a is shown flexibly coupled to frame 500 via spring-loadedcavity 509. While the embodiments shown in FIGS. 1 and 3 are describedas showing no moving parts, any of the scraping elements could beadapted to move in spring-loaded cavities, similar to lock tumblers.This could ensure that multiple scraping elements contact a disc evenwhen the disc flexes. Scraping elements that move into and out ofcavities in a frame will be fixed in two dimensions relative to theframe, and able to move only in one.

FIG. 6 shows method 60 for using an embodiment of the invention, such asthe one shown in FIG. 1. In box 601, spindle 101 on scraper 10 of FIG. 1is inserted through a center hole of a disc. In box 602, the userrotates scraper 10 relative to the disc while maintaining pressure toforce the disc against scraper 10. The disc is then rendered unreadableby the majority of disc readers. FIG. 7 shows method 70 for using anembodiment of the invention, such as the one shown in FIG. 3. Forscraper 30, a disc is inserted into slot 301 in box 701. The user thenslides the disc through the slot in box 702 to render the discunreadable.

As used herein, the term scraping element includes narrow, pointed tipsthat scratch a thin line, as well as broad blades. Also, as used herein,the terms CD and disc include all optically-readable discs, includingcommercially-prevalent 12 cm wide discs. Some embodiments of theinvention, such as the embodiment shown in FIG. 1, may operate reliablyon differently-sized optical media, including optically-readablebusiness cards and minidiscs. Embodiments may also be used onnon-optical media, if the media includes a portion, such as an index orvolume descriptor, that stores information that allows for the use ofthe media.

The embodiments disclosed herein are self-aligning with respect to thevolume descriptor. That is, when a guide engages a disc, whether theguide comprises spindle 101, slot 301, the edge of slot 301, oredge-engaging protrusions 505 a-b, each scraping element will trace apre-determined path across a disc. This is in contrast to any device inwhich a scraping element may trace a path across a disc at an arbitraryposition relative to the index.

Although the present invention and its advantages have been described indetail, it should be understood that various changes, substitutions andalterations can be made herein without departing from the spirit andscope of the invention as defined by the appended claims. Moreover, thescope of the present application is not intended to be limited to theparticular embodiments of the process, machine, manufacture, compositionof matter, means, methods and steps described in the specification. Asone of ordinary skill in the art will readily appreciate from thedisclosure of the present invention, processes, machines, manufacture,compositions of matter, means, methods, or steps, presently existing orlater to be developed that perform substantially the same function orachieve substantially the same result as the corresponding embodimentsdescribed herein may be utilized according to the present invention.Accordingly, the appended claims are intended to include within theirscope such processes, machines, manufacture, compositions of matter,means, methods, or steps.

What is claimed is:
 1. A device for rendering a digital media unusable,wherein the media includes a volume descriptor that stores informationallowing for use of the media, the device comprising: a frame; a firstguide protruding from the frame, operable to engage an outer edge of themedia; a second guide protruding from the frame at a distance of between120 millimeters (mm) and 125 mm away from the first guide, operable toengage the outer edge of the media opposite the first guide, wherein thefirst guide and the second guide are positioned to constrain relativemotion between the frame and the media in at least one dimension; one ormore scraping elements coupled to the frame, wherein at least one of theone or more scraping elements is operable to damage a volume descriptorof the media when the frame is moved with the constrained motionrelative to the media; and a pressure element coupled to at least one ofthe first guide and the second guide, wherein the pressure element isoperable to maintain pressure on the media against at least one of theone or more scraping elements, and wherein the frame, the first guide,the second guide, and the pressure element forms a slot through whichthe media may pass.
 2. The device of claim 1 further comprising: one ormore scraping elements coupled to the pressure element.
 3. The device ofclaim 1 wherein at least one of the one or more scraping elementscomprises a first scraping element positioned between 97 mm and 143 mmfrom the first guide.
 4. The device of claim 1 wherein at least one ofthe one or more scraping elements comprises a sharp point.
 5. The deviceof claim 1 wherein at least one of the one or more scraping elementscomprises a blade.
 6. The device of claim 1 wherein the blade is between1 millimeter (mm) and 3 mm wide.
 7. The device of claim 1 wherein atleast one of the one or more scraping elements is flexibly coupled tothe frame.
 8. A device for a rendering digital media unusable, saiddevice comprising: a frame, said frame comprising a slot between 120millimeters (mm) and 125 mm at the narrowest point of the wide dimensionand between 1.5 mm and 5 mm high at the narrowest point of the narrowdimension; and one or more scraping elements coupled to said frame andprotruding into said slot, wherein at least one of said one or morescraping elements is operable to scrape a surface of said media whensaid media is passed through said slot.
 9. The device of claim 8 whereinat least one of said one or more scraping elements is positioned atapproximately a center point of said wide dimension of said slot. 10.The device of claim 8 wherein at least one of said one or more scrapingelements is positioned between 21 millimeters (mm) and 23 mm from acenter point of said wide dimension of said slot.
 11. The device ofclaim 8 wherein at least one of said one or more scraping elements ispositioned further than 25 millimeters (mm) from a center point of saidwide dimension of said slot.
 12. The device of claim 8 wherein said oneor more scraping elements comprises at least one scraping elementcoupled to said frame on each interior side of said wide dimension ofsaid slot.
 13. A method of rendering digital media unusable, said methodcomprising: inserting a media into a slot in a frame, said slot havingdimensions of between 120 millimeters (mm) and 125 mm at the narrowestpoint of the wide dimension and between 1.5 mm and 5 mm high at thenarrowest point of the narrow dimension and containing one or morescraping elements within 23 mm of a center point of said wide dimension;and passing said media far enough through said slot to scrape a volumedescriptor of said media.